Well the damn weather finally caught up with me. Had to put the boat up yesterday, still had today to go before freezing but I feel like I have wasted a day! Just before putting it up I ran several passes with the GPS on. I found out some interesting things. I run faster when going into the wind, you can sort of tell from the ride that the bow is up slightly more. Ran 70.2 into the wind and about 67 with it.

The hull is a BAJA Force 235 and it does have a very small hook in it. I do plan on removing it to help with bow lift. I am running Mirage Plus 23 or 25. I have tried a standard Mirage but it slipped pretty bad when trimmed and would not carry the bow at all. What mods can be done to help carry the bow? Is the Mirage Plus actually lifting the stern such that the bow drops? I tried a 4 blade something or another and it felt like there was a sky hook on the transom. Stern climbed right out of the water and the bow went down.
Tim T.

The bow lift can be addressed by adding some cup to the Mirage to allow you to trim higher without experienceing blowout this should assist with the bow lift issue. What is your Full Throttle RPM and speed.

Julie
Throttle Up Propellers
877-842-6855
www.throttle-up.com

Well, im not an expert but positive "rake' is what gives you bow lift.

I just tried a Rev4 on my Liberator which also has some hook. Contrary to popular theory, I got more bow lift with the Rev4 four blade then the other props I tried ( 3 blade Rapture, Mirage Plus, Raker). This situation may be unique but it appears that the Rev4 held the water better allowing me to trim higher before blowout. If you can test, give one a try.

As I learned, the lift (bow or stern) depends on where the cup is added. If you cup the blade at the end tail it will add to bow lift and if you cup the blade nearer to the centre of the prop it will add stern lift. How these two interacts with each other I do not know.

With the 25 Mirage Plus about 4500 rpm or so and 67 max, not all the way into the powerband due to cam and intake. With the 23 Mirage Plus tach says 5000 but I bumped up against the Crane ignition rev limiter set at 5200 so I think the tach may be off. With the 23 it will run a solid 70 (light load, cool weather no chop).

This is a stock 502 mag Gen 6 with Lightning’s and a Dart single plane, Holley 800. I used the Dart as the dual plane had very uneven plug reading that even cross jetting could not resolve. Winter plans are to upgrade cam to better suite the intake and headers. I hope to be able to turn the 25 Mirage plus at 4900 to 5200 with the added power.

The lower unit does have a nose cone which reduced the amount of trim tab I need to use. The nose cone is likely holding the bow down some at WOT. In rougher water this is not an issue because a small amount of tab was needed prior to the nose cone being added. It feels as thought the nose cone actually gave a fair amount of stern lift. Now I just need to counteract this with some added bow lift.

Tim T